Adventure Time - Grimoire Card Style: Great Mushroom War
by TrashMech
Summary: This is a series of hypothetical stories that may be related to the War that ended the Human Era. Most of the stories may or may not fit the current Adventure Time lore. Obviously, most of the concepts are not my own and any relations to characters from the show are completely fan made.
1. Hello

**Hello, reader. If you are reading this, you have stumbled upon the beginning of a series of chapters detailing the memories of those who participated in the final War, voluntary or not. The stories were passed down from generation to generation, mutated and changed through the word of mouth. Some were typed and are logged into computer systems while others are obscure rumors told by traveling nomads. Some were pieced together from the ashes of burnt journals while some were washed ashore inside a millennium old, glass bottle.**

 **This is a collection of stories from the apocalyptic war known to us as the Great Mushroom War. To Humanity, however, and the races that fought Humanity, the War was known as Armageddon.**

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Disclaimer: most of these chapters are completely hypothetical and may not fit the current Adventure Time lore. However, I do hope these stories provide some new head canons for those with avid imaginations! Please enjoy the read and please give critiques as this is my first, true fan fiction write!


	2. Prologue - It Begins

**It Has Already Begun.**

The Great Mushroom War did not begin when one of the Old World Human kingdoms launched its weapons. It did not begin when the atom bomb was fully constructed. It did not begin even when the idea of a weapon of such destructive power was conceived.

It began when **the Professor** laid waste to **the King** and his dark subjects. The War began when the demons of the Old World Era showed weakness to Humanity.

When the Professor defeated the King atop his own castle, he laid the seed that would grow into the tree that gives power to the Humans.

The Professor drove his sharpened wooden stake through the King's dead heart, sealing the vampire into the coffin in which his essence would lay for eternity. This was a lie.

"History is written by the victor," yes? The King's apparent fate was written as fact by the Professor himself. The stake did not go through his dark heart – rather it was driven next to it. Through the middle of the King's chest, intentionally. The Professor is a scientist, after all, and he needed a test subject. He needed living proof that the Underworlds did exist and he believed fully that the Vampire King was his key.

* * *

 **They Have Already Lost.**

The King was brought forth in front a crowd of thousands. Eager to see a real monster, hordes of upper class citizens from all over the Ancient Human Kingdoms arrived in swathes to see the beast. Mercifully, the Professor removed the King from his coffin once the Sun's light dipped under the horizon. The Professor does have a crowd to please, and please he will.

In his mind, the King worked over plan after plan. All ended in failure. His bounds were too tight, laced with too much silver, and sprinkled with too much garlic. His body was raised above a body of water, held together inside a barrel that was an elephant wide.

To his surprise - and to the Humans' surprise - the Professor motioned for another coffin to be opened.

It was the King's first lover - before his brides. She was brought forth from her prison and forced to kneel before the thousands. The King began to squirm against his bonds. The tears that were held back for centuries finally flowed.

He watched as the Professor drove his god forsaken stake through her undead heart and his tears stained the ragged shirt he was allowed to wear. As the thousands gasped at the spectacle, the Professor turned towards the King, his eyes filled not of pride, but of sorrow.

As the King's lover began fading into dust, he heard the Professor say those blasted words: "It must be this way. Light and Dark cannot coexist together as one."

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 **But We Are Still Together.**

"However, Light and Dark must exist separately to keep balance to our world. Become our guardians of the night," the Professor added. He was talking to a small crowd of young vampires, all looking eager to be part of the Professor's plan. "We give you pure Human blood, and you give us your might."

The Professor turn towards his partner, who was seated next to him, eyes downcast and shadowed.

"Your Grace? Anything you might add?" he asked with a tiny smile.

The King raised his head, lost in thought. Finally, he uttered a single word.

"No."

As the class left, the King began to mull over the very same plans he had created when his first lover was vanquished. Once again, all ended in failure. The Covens would be destroyed, the Were-beasts subjugated, and the Spirit Worlds controlled.

The Sanguine Bloodlines?

Allied with the Humans as they conquer the galaxy.


	3. Act 1 - Kevin Geraldson, the Swimmer

**Kevin "Mermaid" Geraldson – The Dive**

My friends told me I was a fast swimmer. The fastest out of all of them, actually.

I liked water. I liked how it felt against my body. I took pleasure in submerging myself for as long as possible, even if I could only do so for a short while.

Occasionally, my family and I would go on a fishing trip down the river. It was a really deep river; the local news station reported that there was an entire boat located where it was deepest.

On this trip, however, my father managed to acquire diving suits for us both. It was only us two for this particular dive; he wanted the others to stay above water should anything go wrong. The suits he got were state-of-the-art: full-body, airtight, with a helmet integrated with an water-to-oxygen converter. They also were equipped with helmet lamps that could shine through even the muggiest of water and surprisingly light backup oxygen tanks should the converters fail.

As per usual, I swam faster than my father towards the sunken boat, my father lagging behind to map the hull from the outside. The device he held was small, almost like a laptop. It was waterproof and programmed to map the geography of its surroundings, including this boat my father and I were about to explore.

I waited for my father to catch up, my body floating inside the sunken boat's bridge. I kinda admit it was a little bit spooky being inside the bridge with all the fauna and flora taking over the entire room. My father and I ventured deeper into the boat.

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 **Kevin "Mermaid" Geraldson – The Shore**

I felt them behind me. My squad mates bought me some time. To me, it didn't feel like it was enough.

I swam dolphin-style as fast I could towards the shore. I was the fastest out of everyone I knew, dammit! Those fish-tailed things though were still faster. My squad and I were so focused on exploring that ship, we didn't know we stumbled deep into a goddamn _mermaid_ colony. Real mermaids are chasing a guy nicknamed "mermaid."

How ironic.

It took me a while to realize I was already on the beach, above the water on safe land. I looked over towards the river, my underwater rifle soaked yet still ready to fire. The mermaids breached the surface, some of them still had blood around their lips.

They were so beautiful, so alluring. My commanding officer warned me about this. I wanted to go back; her eyes, her long, brown hair, her curvaceous body. _She_ was pulling me in with her mermaid charm.

The other three next to her had eyes of murder and had bared their teeth of watery death. I wouldn't go back with _her_. When they saw I was able to resist their charm, they made an exaggerated sigh, feigning sadness.

As the mermaids began to dive, I readied my rifle.

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 **Kevin "Mermaid" Geraldson – The Ocean**

My bullets tore through the school of those fish-tails easily. If they screamed, none of us heard it.

The surrounding waters were littered with patrol boats; each of their crews firing both harpoons and lead. It didn't matter where the merfolk swam: if they tried swimming away, our mermaid chaser missiles would catch them. If they tried breaching the water's surface, harpoons would cause their heads explode in a satisfying blast of blood and seawater. If they tried diving deeper into the ocean, our depth charges would be waiting.

Somehow, to me, all this death did not satisfy my own thirst for revenge. As sadistic as it may sound, I still have to remind you that I was the fastest swimmer among everyone I knew.

I was not about to let a bunch of fish-tails ruin my reputation.

In my report I wrote that the operation was successful. The Caribbean was finally clear of any merfolk schools and all of their underwater cities demolished. As I prepared to submit my draft, I looked out into the ocean. Pieces of their former cities floated harmlessly along the surface. Coral, loose sediment... and dead merfolk.

I was eager for the Australian campaign.


	4. Act 1 - Altara Briggs, the Odd

**Altara Briggs, the Odd - Application**

I lived for a while. I am a pure breed vampire and that was super cliché, wow.

No don't worry, I haven't lived for, like, centuries like my parents. I'm twenty-six years old and I am well on my way to becoming the best in my engineering class!

Before you ask, yes I have drank actual human blood before and no I did not force my fangs into someone's neck, for Pete's sake. I drink out of the, uh, blood pouches from the local stores around the corner. Type O, to be exact. Really tasty stuff.

Anyways, yes, I have a major in engineering - mechanical engineering – and I really like working with cars, big machines, and even robots. Some of my projects were really awesome like the one I did a few months ago. The project involved making a ...thing? The launcher that uses magn- a Gauss cannon! A Gauss cannon, yes! That thing launched projectiles using the power of magnets. It was so awesome.

Yes, Mr. Hayden. Yes. Okay. Yes, sir. Will do.

…

Thank you, sir!

Girls... they accepted me into the U.A.C.!

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 **Altara Briggs, the Odd - Advancement**

Hello. Audio log thirty-one. The day is Thursday, the twenty-second of March.

Well, I made some progress with a new Gauss cannon project. First there was the magnetic train lines that I upgraded to be more efficient with the Argent energy, dropping the energy usage down eighty-seven percent. Then there were the gravity lifts where I effectively nullified the nausea induced by the lifts. Then there was... this.

I dare say that my upgrades to my cannon is a massive improvement compare to the... uh... five other... failures... yeah...

Mr. Hayden was getting impatient: he didn't have a face but his robotic body conveyed so much irritation. I won't let him down. My coworkers are all rooting for me still and I am glad to have them on my side.

Anyways, the upgrades included a reduction of recoil so that it could essentially be carried, like an rifle Even with the recoil reduction, the cannon could still fire with enough velocity to puncture the supposedly impenetrable target. Thirty meters of steel, punched through just like that. I will have a video log of the damage done later today.

The other part of the upgrades were its ability to fire any type of metal ammunition, even _freaking_ staples! Imagine, right, you're Gauss cannon's ready to fire, all charged up, and then you see your target covered with staples... and blood.

 _ahem_

Audio log over.

Damn, I'm really getting hungry. What time is it...

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 **Altara Briggs, the Odd - Chase End**

I told them not to chase me, those furballs. I _f-cking_ told them.

But no! They have to be so big and bad and tough that they had to chase me down the forest path. I just want my vacation from Mars to be stress free, is that too much to ask from a vampire girl!?

So my Gauss Rifle was ready and loaded. I kept my own version just for moments like these. I know they were weak to silver but you could just kill those wolves with just a good blast to the heart. The projectile tore through them all, like a nine millimeter bullet goes through red velvet cake. Such a coincidence that they all decided to line up for that perfect shot and _boom._

Six werewolves down.

If I could take a good look, the holes that suddenly appeared on their bodies would line up so neatly. Each body had a hole in their chest where the heart should be, still steaming from the friction of the projectile.

Six werewolves dead. I smiled. My work for the United States was just starting.

Mom and Dad, Alex... I'm sorry. I think I know where I belong.


End file.
